1. Which of the following genotypes would give the highest amount of lacZ expression, and why?

a) A mutation preventing transcription of lacI, the repressor, in glucose media

b) A mutation in the operator sequence in lactose media

c) A mutation in the CAP-recognition site in glucose

2. You are working on the chicken actin gene. You purify mRNA from chickens and run a Northern blot. You use a probe homologous to the 5' end of the gene on the blot, and are surprised to see bands of three different sizes. Explain this data.

3. A mutation changes one amino acid in a protein sequence, located far away from the protein's active site. Yet researchers working on this mutation discover that the mutated protein is nonfunctional. How?